Butterfly Back Draught Shutter.

Butterfly back draught shutters are lightweight dual hinged blade dampers which control airflow in venting and ducting. Manufactured in galvanised steel - the blades are set in a circular casing with two blades opposite one another, that can open and close simultaneously/independently which resemble a butterflies wings and are used in circular/spiral ducting ranging from 100mm diameter up to 250mm.